Dental curable composition

Abstract

A dental polymerizable and curable composition that can be used as a dental composite restorative featuring excellent handling property at the time of filling, a small contraction upon polymerization, a high bending strength, excellent surface smoothness and wear resistance, and a very good matching of color tone to the natural tooth after restored.

Description

TECHNICAL FIELD[0001]The present invention relates to a dental curable composition which can be preferably used as a dental restorative. More specifically, the invention is related to a dental curable composition which can be excellently handled, shrinkage little upon the polymerization, and, when cured, exhibits excellent strength, surface smoothness, wear resistance and color tone that matches with that of natural teeth.BACKGROUND ART[0002]A dental composite restorative is finding a widespread use as a material for restoring the treated teeth since it is capable of imparting a color tone close to that of natural teeth and is easy to handle. In recent years, the dental composite restorative has been used not only for chiefly treating the anterior teeth but also for restoring the posterior teeth which must bear high occlusal pressures.[0003]Generally, the dental composite restorative is chiefly constituted by a polymerizable monomer, a filler and a polymerization catalyst. The handl...

AI Technical Summary

Benefits of technology

[0060]The dental composition of the present invention can be blended with known additives in a range in which they do not greatly impair the effect of the invention. The additives may be a polymerization inhibitor, a pigment, an ultraviolet ray absorber and the like. In order to further improve the strength of the cured product, the dental polymerizable composition of the present invention may be further blended with an inorganic filler having an average particle diameter which is not smaller than 1 μm within a range in which the surface smoothness and wear resistance are not deteriorated.

[0061]In the dental curable composition of the present invention, the greatest feature resides in that the diffusion degree D of the cured product is not smaller than 0.01. Here, the diffusion degree D is an index of light diffusion of when the cured product is irradiated with light, and is defined by the following formula,D={(I20 / cos 20°)+(I70 / cos 70°)} / (2×I0)

[0062]wherein I0, I20 and I70 denote intensities of light that has passed through in the directions of 0°, 20° and 70° C. with respect to the direction of incidence of light when light is permitted to fall perpendicularly onto the surface of a plate-like sample having a thickness of 0.3 mm obtained by curing said dental curable composition.

[0063]The light intensity (luminous intensity) can be easily measured by using a goniophotometer photometer. The trigonometric function (cos) means a cosine in a direction in which the luminous intensity is measured, and the unit of angle is in degrees (°).

[0064]Upon setting the diffusion degree to be not smaller than 0.01, the teeth can be restored by using the dental curable composition of the present invention maintaining a color tone close to that of natural teeth, i.e., maintaining a highly aesthetic appearance. To obtain a color tone that is more adapted, it is desired that the diffusion degree is not smaller than 0.05 and, more preferably, not smaller than 0.08. When the diffusion degree is too high, it becomes difficult to maintain transparency as the dental restorative. It is therefore desired that the diffusion degree is not larger than 0.5 and, more preferably, not larger than 0.3.

[0065]There is no particular limitation on the method of producing the dental curable composition of the present invention. The dental curable composition of the invention, however, can be suitably produced by the following method (production method of the invention).

Problems solved by technology

This dental composite restorative has a feature in that a cured product thereof exhibits a large mechanical strength accompanied, however, by such problems that the polishing property and wear resistance are poor and that it is not capable of clinically offering a finished surface maintaining luster comparable to that of natural teeth.

With the dental composite restorative using such a fine filler, however, the fine filler has such a very large specific surface area that the paste thereof before being cured exhibits a large viscosity.

In order to adjust the viscosity of the paste to such a level that a dentist can use it in the oral cavity, the polymerizable monomer must be blended in inevitably an increased amount causing a decrease in the handling property, an increase in the amount of contraction upon polymerization and a decrease in the mechanical strength.

With the dental composite restorative using the above-mentioned organic / inorganic composite filler, however, the color tone after restored is not necessarily in match with the color tone of the natural teeth and, hence, the aesthetic appearance is not satisfactory.

That is, even if there was selected a conventional material that met the color tone or transparency of a patient's teeth, it was not possible to correctly express the color tone or the quality appeal of the teeth, or the boundary between the filled product and the natural tooth became so distinct that a strong unnatural feeling could not be wiped off.

It has generally been said that light diffusion is one of the factors seriously affecting the aesthetic appearance among the optical properties possessed by the dental composite restorative.

The above publication, however, does not even describe or suggest the improvement in the aesthetic appearance by adjusting the diffusion degree in a system using the organic / inorganic composite filler.

Therefore, the description of the above publication is not at all helpful in trying to bring the color tone into match with the natural tooth by using the system which contains the organic / inorganic composite filler.

Besides, the dental composite restorative using the above organic / inorganic composite filler is not still satisfactory concerning the handling property and mechanical strength, and further improvement is desired.